OrRTMANN: NAIADES OF THE GREEN RIVER DRAINAGE. 179 
Lea’, L. regularis Lea, L. iris Lea, L. planicostatus Lea, L. fatuus 
Lea. To these Simpson, (1914, p. 119), adds: JL. nebulosa (Conr.) 
from “Green River,’’ and (J. c. p. 123): JL. tenera (Lea) from Bowling 
Green. 
All these, with the exception of iris, have been recognized as 
synonyms, for which the oldest name is Micromya nebulosa (Conrad). 
Yet it seems to me, that zris is also merely a form of this species. It 
is distinguished from nebulosa by the character of the rays, which 
are fine, not interrupted, and not very distinct. But M. nebulosa of 
the Tennessee and Cumberland drainages is extremely variable in 
the color-pattern. It mostly has broad, distinct, and often inter- 
rupted rays, which, however, frequently may be missing. Specimens 
with the iris-pattern do exist in the upper Tennessee, and especially 
in the Cumberland. On the other hand, the typical zrzs of the upper 
Ohio drainage never shows the nebulosa-pattern. But then again in 
the Lake-region, the supposed variety of zris, called novi-eboraci Lea, 
distinctly has it (interrupted, distinct rays), and it is impossible for 
me, to distinguish novi-eboraci from nebulosa, when I do not know the 
locality. The Cumberlandian nebulosa is also variable in the color of 
the nacre (whitish, salmon, or purplish), while zr7s and novi-eboract 
are always white inside. 
From Green River at Dunnville I have examined two specimens 
collected by W. J. Clench. One of these is fairly a nebulosa, with 
yellow-brown epidermis, and rather broad, distant, blackish green 
rays, practically uninterrupted, stronger on the posterior part of the 
shell, but present and distinct also on the anterior. The other speci- 
men is more like zr7s, with yellowish green epidermis, and fine, dark 
green rays, not very strongly marked, rather crowded on the posterior 
part, more distant on the anterior part. The nacre in both specimens 
is white. 
This tends to show, that mnebulosa and iris are conspecific (the 
anatomy of the two forms is practically identical), but, of course, the 
material at hand is too meagre to finally settle the question. Addi- 
tional material is to be looked for in small tributaries of Green River. 
The present specimens come from the uppermost station, and it is a 
general rule elsewhere that the nebulosa-iris forms prefer the small 
streams and headwaters. 
4 Given on the same line with L. ovatus, but probably without the intention of 
making them synonyms, which would be ridiculous. 
